### What problem does this PR solve?
Fixes bug & regression introduced by [PR #7187 - refactor: Update Redis
configuration to use StatefulSet instead of deployment with
pvc](https://github.com/infiniflow/ragflow/pull/7187):
1. Fixes bug #7403 - `redis.persistence.enabled` missing from
`helm/values.yaml` causes helm error:
[ERROR] templates/: template: ragflow/templates/redis.yaml:55:24:
executing "ragflow/templates/redis.yaml" at
<.Values.redis.persistence.enabled>: nil pointer evaluating interface
{}.enabled
2. Fixes regression: reverts hardcoded redis.storage.capacity value back
to using variable `redis.storage.capacity` from `helm/values.yaml`.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):
31718581b5